Urea, especially in high concentrations, can be used to treat dry scaly skin, or skin that has thickened to a non-cosmetic or uncomfortable degree. This activity has been attributed to the ability of urea to solubilize and denture protein. Urea can be used to treat xerosis, ichthyosis (e.g., ichthyosis vulgaris), psoriasis, atopic dermatitis, and the like. Such treatment can include itch relief, at least temporary itch relief.
Dermatological compositions of concentrated urea have been formulated in oily bases. Such a oil-based formulations provide a protective layer and localize the urea on the skin. Despite the bias in the industry to formulate in oil-based ointments, Applicant sought to make a water-based, foam-forming composition.
In seeking to formulate a water-based, foam-forming composition, it was discovered that high urea concentrations destabilize formulations that are otherwise stable, water-based dermatological formulations, yielding compositions that form sediments to a degree that makes proper dispensing difficult. Described herein are parameters within which one can formulate stable, water-based compositions of urea at high concentration.